“She died just two years ago, and it is of her death that I wish to speak to you. You can understand that, living the life which I have described, we were little likely to see anyone of our own age and position. We had, however, an aunt, my mother’s maiden sister, Miss Honoria Westphail, who lives near Harrow, and we were occasionally allowed to pay short visits at this lady’s house. Julia went there at Christmas two years ago, and met there a half-pay major of marines, to whom she became engaged. My stepfather learned of the engagement when my sister returned and offered no objection to the marriage; but within a fortnight of the day which had been fixed for the wedding, the terrible event occurred which has deprived me of my only companion.”

Sherlock Holmes had been leaning back in his chair with his eyes closed and his head sunk in a cushion, but he half opened his lids now and glanced across at his visitor.

“Pray be precise as to details,” said he.

“It is easy for me to be so, for every event of that dreadful time is seared into my memory. The manor-house is, as I have already said, very old, and only one wing is now inhabited. The bedrooms in this wing are on the ground floor, the sitting-rooms being in the central block of the buildings. Of these bedrooms the first is Dr. Roylott’s, the second my sister’s, and the third my own. There is no communication between them, but they all open out into the same corridor. Do I make myself plain?”

“Perfectly so.”

“The windows of the three rooms open out upon the lawn. That fatal night Dr. Roylott had gone to his room early, though we knew that he had not retired to rest, for my sister was troubled by the smell of the strong Indian cigars which it was his custom to smoke. She left her room, therefore, and came into mine, where she sat for some time, chatting about her approaching wedding. At eleven o’clock she rose to leave me, but she paused at the door and looked back.

“ ‘Tell me, Helen,’ said she, ‘have you ever heard anyone whistle in the dead of the night?’

“ ‘Never,’ said I.

“ ‘I suppose that you could not possibly whistle, yourself, in your sleep?’

“ ‘Certainly not. But why?’

“ ‘Because during the last few nights I have always, about three in the morning, heard a low, clear whistle. I am a light sleeper, and it has awakened me. I cannot tell where it came from - perhaps from the next room, perhaps from the lawn. I thought that I would just ask you whether you had heard it.’

“ ‘No, I have not. It must be those wretched gypsies in the plantation.’

“ ‘Very likely. And yet if it were on the lawn, I wonder that you did not hear it also.’

“ ‘Ah, but I sleep more heavily than you.’

“ ‘Well, it is of no great consequence, at any rate.’ She smiled back at me, closed my door, and a few moments later I heard her key turn in the lock.”

“Indeed,” said Holmes. “Was it your custom always to lock yourselves in at night?”

“Always.”

“And why?”

“I think that I mentioned to you that the doctor kept a cheetah and a baboon. We had no feeling of security unless our doors were locked.”

“Quite so. Pray proceed with your statement.”